Add tests to repository

tests/.gitignore

tests/argon-small/BrownDyn.bd

tests/argon-small/performance

tests/argon-small/pmf.dx

tests/argon-small/run.sh

tests/argon-small/vdw.dat

tests/argon-small/vdw.py

tests/argon/BrownDyn.bd

tests/argon/analysis/Makefile

tests/argon/analysis/get-data.tcl

tests/argon/analysis/plot.plt.py

tests/argon/analysis/plotTools.py

tests/argon/performance

tests/argon/pmf.dx

tests/argon/run.sh

tests/argon/vdw.dat

tests/argon/vdw.py

tests/bond/BrownDyn.bd

tests/bond/analysis/Makefile

tests/bond/analysis/boltzmann-check.plt.py